Multiplex PCR reveals population structure in an inbred communal bird.

Abstract

We sampled communally breeding p[u]keko (Porphyrio melanotus melanotus, family Rallidae) populations on the North (T[a]wharanui Park) and South (Otokia Reserve) Islands of New Zealand that differ in climate and ecology. North Island populations have year-round territories, philopatry, and form kin groups, resulting in inbreeding. South Island populations have seasonal territories, high dispersal rates, and form non-kin groups, leading to outbreeding. Given behavioural evidence of inbreeding we predicted that the North Island population would exhibit lower heterozygosity and higher inbreeding coefficients than the South Island population. We hypothesized that the South Island population originated via a range expansion from the north and predicted that South Island birds would have lower allelic diversity due to founder effects. To test these predictions, we developed microsatellite primers, optimized multiplex PCRs, and genotyped breeding groups from the North and South Island. Breeding groups from North Island were genetically differentiated, whereas population structure was not detected in the South Island birds. North Island birds had higher inbreeding coefficients and levels of within group kinship, but not allelic diversity, compared to South Island birds. Our results are thus inconclusive about whether the South Island population originated via a range expansion from the north. This pilot study validated microsatellite markers and PCR methods and is the first genetic analysis of population structure and relatedness within communal breeding p[u]keko groups. These genetic tools will be used for larger-scale studies to help resolve the origins of the South Island population and provide further insights into the effects of ecology and behaviour on inbreeding, reproductive success, and population demographics in this species. P[u]keko may provide an excellent model for experimental analyses of inbreeding effects on wild avian populations without the attendant concerns that come with small, endangered populations. This work may thus inform conservation efforts, including translocations of endangered species.